Imaging studies in movement disorders.

Imaging presynaptic dopaminergic markers provides key insights into the pathophysiology of Parkinson's Disease (PD) and is becoming an important endpoint in clinical trials of potential disease-modifying therapies for PD. The further development of this area includes work to optimize targets for accurate and reliable measurement of disease progression. Ultimately, it may be possible to elaborate these markers to fine-tune our understanding of those patients who might be enrolled in a trial. For example, PD patients may be characterized as slow vs. fast progressors based on imaging measures, providing the opportunity to optimize the trial recruitment to demonstrate the greatest impact in Phase 2 evaluations of neuroprotective agents. Further, while dopamine degeneration is a crucial feature of PD, it is clear that there is widespread degeneration in the brain in PD and that many clinical manifestations of PD are likely not due to dopamine deficiency. It is reasonable to imagine that the characterization of additional targets outside the dopamine system could aid in both the molecular basis for disease characterization and ultimately optimization of therapeutics.